Method of removing drilling-tools.



w. 0. SNELLING.

METHOD OF REMOVING DRILLING TOOLS.

APPLICATION FILED AUG.25, I9I5.

Patented Sept. 1916.

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ATTORNEY rrnn s'rnrns rA'rnNr ornrcn.

WALTER O. SNELLING, 0F PITTSBURGH, PENNSYLVANIA.

METHOD OF REMOVING DRILLING-TOOLS.

Specification of Letters Patent.

Patented Sept. 5, 1916..

Application filed August 25, 1915. Serial No. 47,262.

To all whom it may concern:

Be it known that I, WALTER O. SNELLING, a citizen of the United States,and aresident of Pittsburgh, in the county of Alledrilling tools, casingparts or other metallic obstructions from the deep wells that arecommonly drilled for oil, gas, or water.

In the accompanying drawing, Figure 1 is a general view, partlyin sideelevation and partly in vertical section, of a welldrilling installationor rig, showing a string of drilling tools jammed at the bottom of thehole, and Fig. 2is a vertical sectional view of a partly drilled well,showing a jammed and broken string of tools, and illustrating onemodification of my present invention.

In the drilling of deep wells for oil, gas or water, the loss of astring of drilling tools in a not infrequent occurrence, and muchattention has been paid to devising so-called fishing methods andapparatus for recovering such lost tools or parts of tools. However, inspite of the most improved fishing methods, tools are often lost whichcannot be'recovered in this manner,

and which remain as a serious obstruction in the well. In such a case,it is necessary either to find means for drilling around theobstruction, a matter of much difficulty, or to abandon the well at aconsiderable loss.

According to my present invention, I dispose of broken tools, casingparts or other oxidizable metallic obstructions by making such anobstruction the positive electrode or anode of an electrolytic'cell, inthe presence of a suitable electrolyte and preferably with theassistance of strong electric cur rents. The effect of this treatment isto transform the metal, either wholly or in part, into loose masses ofoxide. The process of electrolytic oxidation may be carried only farenough to reduce the size of the metallic object sufficiently to permitit to be dislodged and removed by ordinary fishing methods; or the metalmay be completely oxidized, the resulting oxid slimes being readilyremoved or penetrated in renewed drilling operations.

Fig. 1 of the accompanying drawing illustrates a situation to which mypresent invention may be applied, and shows a well drilling rigconsisting of the usual derrick 1, a walking beam 2, oscillated about apivot 3 by means of a crank-4 and a connecting rod 5, and a boiler 6forsupplying steam to anengine which, together with the other operatingmechanism, is housed by a building 7. The well 8 is exaggerated indiameter for the purpose of illustration and is shown sunk to aconsiderable depth, which .may be several hundreds or thousands of feet,through various strata of earth. The upper section of the well isprovided with the usual casing 9. At the bottom of the well is a stringof drilling tools10, composed of the usual bit, jars and sinker, theupper end of the string of tools being shown in the bent and distortedcondition in which they are left after unsuccessful fishing operationsand the operating cable 11 being indicated as having parted and left thetools ,below. It is my present object to remove lost and jammed tools,such as those shown, by partial or complete electrolysis.

Many drilled wells, especially those that are bored for oil and gas,contain saline solutions, and in such cases, no additional electrolyteis necessary for my purpose. When such solutions are not alreadypresent, I prefer to introduce into the well a quantity of common salt,together with sufficient water, if the well is dry, to submerge themetallic parts to be electrolyzed. ,While common salt is a convenientelectrolyte for my purpose, any other electrolyte may be used that hasa-corrosive action upon iron under the conditions described below.

The principles of my invention may be applied in several ways, thesimplest of which consists in providing a suitable electrolyte andlowering into the well, in con tact with the tools, a bar 12 of copperor of some other'material that is electrolytically negative with respectto iron. Such a bar, when brought into contact with the iron as tion.

shown in Fig. 1, forms a short-circuited galvanic cell, and generatessufficient current to cause the negative ions of the electrolyte to movetoward the iron electrode, where they give up their electric charges,and decompose a portion of the Water present. The nascent oxygen thusevolved corrodes the iron at a substantial rate, and the corrosionprocess may be assisted by raising and dropping the bar 12 by means of asuspending cord or wire 13, in order to remove the adhering oxids fromthe iron tools and to expose fresh surfaces to the electrolytic ac- Thisprocess, however, is relatively slow, and I therefore prefer tovmake useof electric currents of considerable magnitude, in order to hasten theoxidation of the tools.

Portable direct-current electric generators and motor-generators setsare now in common use for electric welding and for other direct-currentservice, and such portable generators are frequently capable ofproducing currents, at low voltages, of 300 or 400 amperes. Suchgenerators are well adapted for my present purpose, and may be driveneither by electric motors or by gas.

engines, according to the circumstances under which they are used. Fig.2 of the accompanying drawing shows an arrangement for utilizing agenerator set of this kmd 1n the electrolysis of drilling toolsaccording to my invention.

The generator 15, driven by a gas engine 16, is brought near the surfaceopening of the well 8, and its positive terminal is connected, by meansof an insulated conductor 17, with a'contact member 18, which is suit-,ably of coppper, and which is lowered into the well into contact'withthe tools 10. The negative terminal of the generator 15 should be wellgrounded, suitably by connecting it to the well casing 9. Current fromthe generator flows through the conductor 17 andthe contact member 18 tothe tools10, and then through the electrolyte to the earth.

7 The tools 10 are thus made the positive electrode of a powerfulelectrolytic cell, of which the earth forms the negative electrode, andthey are rapidly corroded by the ,ensuing oxidizing action. The ironoxids produced in contactwith the irontend to set up small galvaniccouples which promote the destruction of the iron by self-corrosion. Thevoltage of the generator should of course be as low as' possible, inorder to reduce theconsumption of power and also to prevent leakage ofcurrent from the conductor 17 to-the well casing 9.

As indicated above, the electrolysis of the iron may be either partialor complete.

Thus, it may be only necessary to removea small outer portion of theiron to enable the tools to be dislodged and removed by ordinary fishingmethods, or it may be more ploy alternating current, by adding to thei,iee,sie

oxids from time to time, in order to mainm tain free access of theelectrolyte to the iron.

While the use of direct current is ordinarily to be preferred incarrying out my present method, it is also possible to em- 5 electrolytea chemical agent such as a solu I ble carbonate which forms an insolublecompound with the iron dissolved at each alternation of the current inthe electrolyzing direction. For example, sodium carbonate may be addedto the electrolyte for this purpose, and under these circumstances itmay be found desirable to substitute a carbon electrode for the coppercontact member 18. Y

' My invention may be variously modified without exceeding the scope ofthe appended claims, and it is therefore to be understood that thestructural details which I have shown and described are to be construedas being illustrative only, and not as imposing limitiations upon theclaims.

I claim as my invention:

1. The method of disposing of well-drilling appliances embeddedin theearth that 95 comprises electrolytically destroying the metalliccharacter of at least a portion of the metal composing such appliances.

2. The method of disposing of well-drilling tools embedded in the earththat comprises electrolytically oxidizing such tools.

3. The method of disposing of welldrilling tools embedded in the earththat comprises making such tools the anode of an electrolytic cell andthereby transforming 105 the metal. composing the tools at leastpartially into a non-metallic condition.

4. The method of disposing of well-drilling tools embedded in the earththat comprises making such tools the anode of an electrolytic cell andpassing electrolyzing current through the cell thus formed there bytransforming the metal composing the tools at. least partially into anon-metallic condition. 115

5. The method of disposing of well-drilling tools embedded in the earththat comprises making such tools the anode of an electrolytic cell,passing an electrolyzing current through the cell thus formed, and 12aremoving the non-metallic ferruginous reaction products.

6. The method of disposing of well-drilling tools embedded in a wellthat comprises providing sufficient electrolyte in the well tosubmergethe tools, lowering an electric contact member into engagementwith the tools, and supplying an electrolyzing current to the saidcontact member.

7.. The method of disposing of well-drilling tools embedded in the earththat comsubscribed my name this 23rd day of prises lowering anslllecfiric mintact lllnem'ber August, 1915. into en a, ementwi 't e 00sint e presence 0 5n electrolyte, and shpplying an WALTER SNELLING 5electrolyzing current to the said contact Witnesses:

member. M. R. MCKEOWN,

In testimony whereof, I have hereunto J. G. KAISER.

